Table of Contents
Compost maturity indicators are divided into three categories: physical indicators, chemical indicators (including hummus), and biological indicators.
The evaluation methods of compost maturity are divided into four categories: apparent analysis method, chemical analysis method, spectral analysis method, and plant growth analysis method, which are similar to the former classification method.
Below, Tianci Heavy Industry will explain it in detail for you.
A detailed explanation of the maturity index of organic fertilizer fermentation:
Physical index or apparent analysis index:
Refers to some intuitive properties of changes in the composting process, such as temperature, smell, and color. Specifically:
1. Temperature: After the composting starts, the temperature of the pile body is gradually increased and then decreased. After the pile body is decomposed, the temperature of the pile body is consistent with the ambient temperature or slightly higher than the ambient temperature, and generally does not change significantly, so the temperature is the composting process One of the important routine testing indicators in the
2. Odor: Composting raw materials have an unpleasant odor, and will produce unpleasant gases such as H2S and NO during the composting process. After a good composting process, these odors will gradually weaken and disappear after the composting, so the odor can also be As an indicator of compost maturity;
3. Color: The compost gradually turns black during the composting process, and the compost product after decomposing is dark brown and black. The color can also be used as a criterion;
4. Absorbance changes: The optical properties of the water extracts of composting at different times at wavelengths of 280 nm, 465 nm, and 665 nm showed that the small amount of individual organic components inhibited the absorption of short waves, while the wavelength of 665 nm The visible light has less effect, so by detecting the absorbance change of the compost extract at a wavelength of 665 nm, the compost maturity can be reflected.
As physical indicators are difficult to quantitatively characterize the changes in compost composition during the composting process, it is more commonly used to evaluate the compost maturity by analyzing the changes in the chemical composition or chemical properties of the compost during the composting process.
These chemical indicators include organic matter change indicators, ammonia nitrogen indicators, humification indicators, carbon to nitrogen ratio, and organic acids. The specific content includes:
1. During the composting process, the unstable organic matter in the pile is decomposed and converted into carbon dioxide, water, minerals, and stabilized organic matter. The organic matter content of the pile changes significantly, so some parameters that reflect the change of organic matter (such as COD, BOD) And VS, etc.) and the change law of certain organic matter during the composting process to characterize the maturity;
2. In the process of biochemical degradation of compost, nitrogen-containing components are degraded to produce ammonia. In the later stage of composting, part of ammonia is oxidized to nitrite and nitrate, so the presence of nitrite or nitrate can be used to judge maturity. And because the measurement of these two indicators is relatively fast and simple, it has good practical value;
3. The composting process is accompanied by the process of humification. Studying the changes of various humification parameters is an important method to evaluate maturity. From this, CEC (cation exchange capacity), humus HS, humic acid HA, fulvic acid FA, Some parameters such as FF and non-humus components in Fuli are used to evaluate the maturity of compost;
4. The carbon source is the energy used by microorganisms, and the nitrogen source is the nutrients of microorganisms. The change of carbon and nitrogen is one of the basic characteristics of composting. C/N (solid phase) is often used to evaluate the parameters of maturity. Studies have also pointed out that the metabolism of microorganisms in the degradation of compost raw materials occurs in the water-soluble phase, so the index of water-soluble organic carbon/organic nitrogen can be used as a parameter of compost maturity;
5. Organic acids are widely present in unripe compost, and the degree of compost maturity can be evaluated by studying the changes of organic acids.
Changes in the activity of microorganisms in the compost and the effect of compost on plant growth are often used to evaluate the maturity of compost. These indicators mainly include respiration, biological activity, and seed germination rate experiments. Specifically:
1. Compost is a stable product rich in humus, and the microorganisms are in a dormant state. At this time, the biochemical degradation rate of humus and the production of carbon dioxide and oxygen consumption are slow. Therefore, the production of carbon dioxide and the rate of oxygen consumption of microorganisms can be used as a reflection of maturity. index;
2. At the same time, parameters that reflect changes in microbial activity, such as enzyme activity, ATP, and the number and type of microorganisms, can also be used to characterize the stability and maturity of compost;
3. Immature compost products have an inhibitory effect on the growth of plants. Therefore, the growth status of plants in the mixture of compost and soil can be used to evaluate the maturity of compost. Considering the practical significance of compost maturity, this is the final and most convincing one. Power evaluation method.
Spectral analysis method:
Spectroscopic analysis can understand the composting process and maturity issues from the perspective of material structure. Up to now, 13C-NMR and infrared spectroscopy have been used more. Infrared spectroscopy can identify the characteristic functional groups of compounds. Nuclear magnetic resonance can provide organic skeleton information of the molecule.